Izzo Alex Duetto I brew pressure low after expansion valve seat replaced

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BAEvans
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Joined: 16 years ago

#1: Post by BAEvans »

All:
Need some help.
My Alex Duetto I (plumbed in) was filling the reservoir daily, diagnosed as expansion valve seat fatigue.
I got a new part and replaced it yesterday.
Now the brew pressure is markedly low (3 - barely above line pressure).
Will call Chris Coffee tomorrow, but wonder if anyone can help. Can this happen if the adjustment on the expansion valve is off? I understand on a rotary pump machine the valve determines the maximum brew pressure allowed, so is that the problem - set too low? If so, should it go in or out to adjust - logic suggests "in" to raise the pressure by putting more spring pressure on the valve seat. Perhaps the new valve seat is somewhat different size (it is a different material and color).
Or in replacing the valve seat, did I inadvertently bump something out of adjustment? It was the only thing I touched and there doesn't seem to be any leak at the joints I loosened to get the expansion valve out.

Help would be appreciated.
Bruce

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BAEvans (original poster)
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#2: Post by BAEvans (original poster) »

Being impatient, I just cracked it back open and with trial and error determined that screwing the adjust nut "in" lowered the brew pressure further, and backing it "out" raised the brew pressure to the appropriate level.
Definitely a different setting than before I replaced the expansion valve seat, so the new one required a different setting.
Just a warning to all who replace the Duetto I expansion valve seat (they seem to deteriorate at about 4-5 years; main effect is to quickly fill the reservoir to overflowing) not to put everything back together until verifying that the brew pressure is correct.
The repair, however, is quite easy.

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JohnB.
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#3: Post by JohnB. »

BAEvans wrote: I understand on a rotary pump machine the valve determines the maximum brew pressure allowed, so is that the problem - set too low?
On a rotary pump machine the expansion valve setting determines the maximum pressure in the brew boiler before the valve starts to drip & bleed off pressure. It has nothing to do with brew pressure at the group. Typically it would be set to open if the brew boiler pressure goes over 12 bar. Brew pressure is adjusted at the pump.

If you have a vibe pump machine then you have an OPV, not an expansion valve & that does control brew pressure.
LMWDP 267

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BAEvans (original poster)
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Joined: 16 years ago

#4: Post by BAEvans (original poster) »

True enough.
In this case, the rotary pump pressure had (long) been properly adjusted, and the problem developed after I replaced the valve seat in the expansion valve; presumably the typical setting of 12 bar was no longer present. Either I didn't match the old setting when I replaced the valve seat - which involved completely removing the adjustment screw to gain access - or the new seat was different. The brew pressure never rose above 3 accompanied by discharge of water into the reservoir to which the output of the Duetto I expansion valve is directed. The sound of the pump was also much louder.
Once I adjusted the valve, normal operation resumed with a normal brew pressure.